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Ibanez Gaspar V, McMorrow T. Models of Renal Carcinogenesis: Characterisation and Novel Therapeutics. Toxicol Lett 2021. [DOI: 10.1016/s0378-4274(21)00608-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Wiebe E, Kelly M, McMorrow T, Tremblay-Huet S, Sum B, Hennawy M. How the experience of medical assistance in dying changed during the COVID-19 pandemic in Canada: a qualitative study of providers. CMAJ Open 2021; 9:E400-E405. [PMID: 33863798 PMCID: PMC8084544 DOI: 10.9778/cmajo.20200163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND In March 2020, all levels of government introduced various strategies to reduce the impact of the COVID-19 pandemic. The purpose of this study was to document how the experience of providing medical assistance in dying (MAiD) changed during the COVID-19 pandemic. METHODS We conducted a qualitative study using semistructured interviews with key informants in Canada who provided or coordinated MAiD before and during the COVID-19 pandemic. We interviewed participants from April to June 2020 by telephone or email. We collected and analyzed data in an iterative manner and reached theme saturation. Our team reached consensus on the major themes and subthemes. RESULTS We interviewed 1 MAiD coordinator and 15 providers, including 14 physicians and 1 nurse practitioner. We identified 4 main themes. The most important theme was the perception that the pandemic increased the suffering of patients receiving MAiD by isolating them from loved ones and reducing available services. Providers were distressed by the difficulty of establishing rapport and closeness at the end of life, given the requirements for physical distancing and personal protective equipment. They were concerned about the spread of SARS-CoV-2, and found it difficult to enforce rules about distancing and the number of people present. Logistics and access to MAiD became more difficult because of the new restrictions, but there were many adaptations to solve these problems. INTERPRETATION Providers and coordinators had many challenges in providing MAiD during the COVID-19 pandemic, including their perception that the suffering of their patients increased. Some changes in how MAiD is provided that have occurred during the pandemic, including more telemedicine assessments and virtual witnessing, are likely to remain after the pandemic and may improve service.
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Affiliation(s)
- Ellen Wiebe
- Department of Family Medicine (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London, UK; University of Ontario Institute of Technology (McMorrow), Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Sherbrooke, Que.; University of British Columbia (Sum, Hennawy), Vancouver, BC
| | - Michaela Kelly
- Department of Family Medicine (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London, UK; University of Ontario Institute of Technology (McMorrow), Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Sherbrooke, Que.; University of British Columbia (Sum, Hennawy), Vancouver, BC
| | - Thomas McMorrow
- Department of Family Medicine (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London, UK; University of Ontario Institute of Technology (McMorrow), Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Sherbrooke, Que.; University of British Columbia (Sum, Hennawy), Vancouver, BC
| | - Sabrina Tremblay-Huet
- Department of Family Medicine (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London, UK; University of Ontario Institute of Technology (McMorrow), Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Sherbrooke, Que.; University of British Columbia (Sum, Hennawy), Vancouver, BC
| | - Brian Sum
- Department of Family Medicine (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London, UK; University of Ontario Institute of Technology (McMorrow), Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Sherbrooke, Que.; University of British Columbia (Sum, Hennawy), Vancouver, BC
| | - Mirna Hennawy
- Department of Family Medicine (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London, UK; University of Ontario Institute of Technology (McMorrow), Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Sherbrooke, Que.; University of British Columbia (Sum, Hennawy), Vancouver, BC
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Wiebe E, Kelly M, McMorrow T, Tremblay-Huet S, Hennawy M. Assessment of capacity to give informed consent for medical assistance in dying: a qualitative study of clinicians' experience. CMAJ Open 2021; 9:E358-E363. [PMID: 33849985 PMCID: PMC8084565 DOI: 10.9778/cmajo.20200136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Under the Canadian Criminal Code, medical assistance in dying (MAiD) requires that patients give informed consent and that their ability to consent is assessed by 2 clinicians. In this study, we intended to understand how Canadian clinicians assessed capacity in people requesting MAiD. METHODS This qualitative study used interviews conducted between August 2019 and February 2020, by phone, video and email, to explore how clinicians assessed capacity in people requesting MAiD, what challenges they had encountered and what tools they used. The participants were recruited from provider mailing listserves of the Canadian Association of MAiD Assessors and Providers and Aide médicale à mourir. Interviews were audio-recorded and transcribed verbatim. The research team met to review transcripts and explore themes as they emerged in an iterative manner. We used abductive reasoning for thematic analysis and coding, and continued to discuss until we reached consensus. RESULTS The 20 participants worked in 5 of 10 provinces across Canada, represented different specialties and had experience assessing a total of 2410 patients requesting MAiD. The main theme was that, for most assessments, the participants used the conversation about how the patient had come to choose MAiD to get the information they needed. When the participants used formal capacity assessment tools, this was mostly for meticulous documentation, and they rarely asked for psychiatric consults. The participants described how they approached assessing cases of nonverbal patients and other challenging cases, using techniques such as ensuring a quiet environment and adequate hearing aids, and using questions requiring only "yes" or "no" as an answer. INTERPRETATION The participants were comfortable doing MAiD assessments and used their clinical judgment and experience to assess capacity in ways similar to other clinical practices. The findings of this study suggest that experienced MAiD assessors do not routinely require formal capacity assessments or tools to assess capacity in patients requesting MAiD.
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MESH Headings
- Attitude of Health Personnel
- Canada
- Clinical Decision-Making/ethics
- Clinical Decision-Making/methods
- Codes of Ethics
- Euthanasia, Active, Voluntary/ethics
- Euthanasia, Active, Voluntary/legislation & jurisprudence
- Euthanasia, Active, Voluntary/psychology
- Guidelines as Topic
- Humans
- Informed Consent/standards
- Mental Competency
- Nurses
- Physicians
- Practice Patterns, Physicians'/ethics
- Practice Patterns, Physicians'/standards
- Professional Practice/statistics & numerical data
- Qualitative Research
- Right to Die/ethics
- Right to Die/legislation & jurisprudence
- Social Control, Formal/methods
- Suicide, Assisted/ethics
- Suicide, Assisted/legislation & jurisprudence
- Suicide, Assisted/psychology
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Affiliation(s)
- Ellen Wiebe
- Department of Family Practice (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London School of Hygiene and Tropical Medicine, Department of Epidemiology and Population Health, London, UK; Ontario Tech University (McMorrow), Faculty of Social Science and Humanities, Legal Studies, Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Faculty of Law, Sherbrook, Que.; University of British Columbia (Hennawy), Kelowna, BC
| | - Michaela Kelly
- Department of Family Practice (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London School of Hygiene and Tropical Medicine, Department of Epidemiology and Population Health, London, UK; Ontario Tech University (McMorrow), Faculty of Social Science and Humanities, Legal Studies, Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Faculty of Law, Sherbrook, Que.; University of British Columbia (Hennawy), Kelowna, BC
| | - Thomas McMorrow
- Department of Family Practice (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London School of Hygiene and Tropical Medicine, Department of Epidemiology and Population Health, London, UK; Ontario Tech University (McMorrow), Faculty of Social Science and Humanities, Legal Studies, Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Faculty of Law, Sherbrook, Que.; University of British Columbia (Hennawy), Kelowna, BC
| | - Sabrina Tremblay-Huet
- Department of Family Practice (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London School of Hygiene and Tropical Medicine, Department of Epidemiology and Population Health, London, UK; Ontario Tech University (McMorrow), Faculty of Social Science and Humanities, Legal Studies, Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Faculty of Law, Sherbrook, Que.; University of British Columbia (Hennawy), Kelowna, BC
| | - Mirna Hennawy
- Department of Family Practice (Wiebe), University of British Columbia, Vancouver, BC; University of London (Kelly), London School of Hygiene and Tropical Medicine, Department of Epidemiology and Population Health, London, UK; Ontario Tech University (McMorrow), Faculty of Social Science and Humanities, Legal Studies, Oshawa, Ont.; Université de Sherbrooke (Tremblay-Huet), Faculty of Law, Sherbrook, Que.; University of British Columbia (Hennawy), Kelowna, BC
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Tremblay-Huet S, McMorrow T, Wiebe E, Kelly M, Hennawy M, Sum B. The impact of the COVID-19 pandemic on medical assistance in dying in Canada and the relationship of public health laws to private understandings of the legal order. J Law Biosci 2020; 7:lsaa087. [PMID: 33537150 PMCID: PMC7799035 DOI: 10.1093/jlb/lsaa087] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/20/2020] [Accepted: 11/01/2020] [Indexed: 05/11/2023]
Abstract
Drawing on interviews we conducted with 15 medical assistance in dying (MAiD) providers from across Canada, we examine how physicians and nurse practitioners reconcile respect for the new, changing rules brought upon by the coronavirus disease 2019 (COVID-19) pandemic, along with their existing legal obligations and ethical commitments as health care professionals and MAiD providers. Our respondents reported situations where they did not follow or did not insist on others following the applicable public health rules. We identify a variety of techniques that they deployed either to minimize, rationalize, justify or excuse deviations from the relevant public health rules. They implicitly invoked the exceptionality and emotionality of the MAiD context, especially in the time of COVID, when offering their accounts and explanations. What respondents relate about their experiences providing MAiD during the COVID pandemic offers occasion to reflect on the role actors themselves play in giving meaning (if not coherence) to the potentially conflicting normative expectations to which they are subject.
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Affiliation(s)
| | - Thomas McMorrow
- Faculty of Social Science and Humanities, Ontario Tech University, Oshawa, Ontario, Canada
| | - Ellen Wiebe
- Department of Family Practice, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michaela Kelly
- London School of Hygiene and Tropical Medicine, University of London, London, UK
| | - Mirna Hennawy
- Department of Family Practice, University of British Columbia, Vancouver, British Columbia, Canada
| | - Brian Sum
- Department of Family Practice, University of British Columbia, Vancouver, British Columbia, Canada
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Herwig R, Gmuender H, Corvi R, Bloch KM, Brandenburg A, Castell J, Ceelen L, Chesne C, Doktorova TY, Jennen D, Jennings P, Limonciel A, Lock EA, McMorrow T, Phrakonkham P, Radford R, Slattery C, Stierum R, Vilardell M, Wittenberger T, Yildirimman R, Ryan M, Rogiers V, Kleinjans J. Inter-laboratory study of human in vitro toxicogenomics-based tests as alternative methods for evaluating chemical carcinogenicity: a bioinformatics perspective. Arch Toxicol 2015; 90:2215-2229. [PMID: 26525393 DOI: 10.1007/s00204-015-1617-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/19/2015] [Indexed: 01/29/2023]
Abstract
The assessment of the carcinogenic potential of chemicals with alternative, human-based in vitro systems has become a major goal of toxicogenomics. The central read-out of these assays is the transcriptome, and while many studies exist that explored the gene expression responses of such systems, reports on robustness and reproducibility, when testing them independently in different laboratories, are still uncommon. Furthermore, there is limited knowledge about variability induced by the data analysis protocols. We have conducted an inter-laboratory study for testing chemical carcinogenicity evaluating two human in vitro assays: hepatoma-derived cells and hTERT-immortalized renal proximal tubule epithelial cells, representing liver and kidney as major target organs. Cellular systems were initially challenged with thirty compounds, genome-wide gene expression was measured with microarrays, and hazard classifiers were built from this training set. Subsequently, each system was independently established in three different laboratories, and gene expression measurements were conducted using anonymized compounds. Data analysis was performed independently by two separate groups applying different protocols for the assessment of inter-laboratory reproducibility and for the prediction of carcinogenic hazard. As a result, both workflows came to very similar conclusions with respect to (1) identification of experimental outliers, (2) overall assessment of robustness and inter-laboratory reproducibility and (3) re-classification of the unknown compounds to the respective toxicity classes. In summary, the developed bioinformatics workflows deliver accurate measures for inter-laboratory comparison studies, and the study can be used as guidance for validation of future carcinogenicity assays in order to implement testing of human in vitro alternatives to animal testing.
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Affiliation(s)
- R Herwig
- Department Computational Molecular Biology, Max-Planck-Institute for Molecular Genetics, Ihnestr. 73, 14195, Berlin, Germany.
| | - H Gmuender
- Genedata AG, Margarethenstrasse 38, 4053, Basel, Switzerland
| | - R Corvi
- European Union Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM), Institute for Health and Consumer Protection (IHCP), European Commission Joint Research Centre, TP 126, Via E. Fermi 2749, 21027, Ispra, Italy
| | - K M Bloch
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - A Brandenburg
- Genedata AG, Margarethenstrasse 38, 4053, Basel, Switzerland
| | - J Castell
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Valencia, Av. Blasco Ibanez 15, 46010, Valencia, Spain
| | - L Ceelen
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090, Brussels, Belgium
| | - C Chesne
- Biopredic International, Parc d'affaires de la Bretèche, Bldg. A4, 35760, St Gregoire, France
| | - T Y Doktorova
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090, Brussels, Belgium
| | - D Jennen
- Department of Toxicogenomics, Maastricht University, Maastricht, The Netherlands
| | - P Jennings
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - A Limonciel
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - E A Lock
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - T McMorrow
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - P Phrakonkham
- European Union Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM), Institute for Health and Consumer Protection (IHCP), European Commission Joint Research Centre, TP 126, Via E. Fermi 2749, 21027, Ispra, Italy
| | - R Radford
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - C Slattery
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - R Stierum
- Department of Risk Analysis for Products in Development, Netherlands Organisation for Applied Scientific Research (TNO), Utrechtseweg 48, 3704 HE, Zeist, The Netherlands
| | - M Vilardell
- Department Computational Molecular Biology, Max-Planck-Institute for Molecular Genetics, Ihnestr. 73, 14195, Berlin, Germany
| | - T Wittenberger
- Genedata AG, Margarethenstrasse 38, 4053, Basel, Switzerland
| | - R Yildirimman
- Department Computational Molecular Biology, Max-Planck-Institute for Molecular Genetics, Ihnestr. 73, 14195, Berlin, Germany
| | - M Ryan
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - V Rogiers
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090, Brussels, Belgium
| | - J Kleinjans
- Department of Toxicogenomics, Maastricht University, Maastricht, The Netherlands
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Flint J, Tufarelli C, Peden J, Clark K, Daniels RJ, Hardison R, Miller W, Philipsen S, Tan-Un KC, McMorrow T, Frampton J, Alter BP, Frischauf AM, Higgs DR. Comparative genome analysis delimits a chromosomal domain and identifies key regulatory elements in the alpha globin cluster. Hum Mol Genet 2001; 10:371-82. [PMID: 11157800 DOI: 10.1093/hmg/10.4.371] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have cloned, sequenced and annotated segments of DNA spanning the mouse, chicken and pufferfish alpha globin gene clusters and compared them with the corresponding region in man. This has defined a small segment ( approximately 135-155 kb) of synteny and conserved gene order, which may contain all of the elements required to fully regulate alpha globin gene expression from its natural chromosomal environment. Comparing human and mouse sequences using previously described methods failed to identify the known regulatory elements. However, refining these methods by ranking identity scores of non-coding sequences, we found conserved sequences including the previously characterized alpha globin major regulatory element. In chicken and pufferfish, regions that may correspond to this element were found by analysing the distribution of transcription factor binding sites. Regions identified in this way act as strong enhancer elements in expression assays. In addition to delimiting the alpha globin chromosomal domain, this study has enabled us to develop a more sensitive and accurate routine for identifying regulatory elements in the human genome.
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Affiliation(s)
- J Flint
- MRC Molecular Haematology Unit, Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK
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McMorrow T, van den Wijngaard A, Wollenschlaeger A, van de Corput M, Monkhorst K, Trimborn T, Fraser P, van Lohuizen M, Jenuwein T, Djabali M, Philipsen S, Grosveld F, Milot E. Activation of the beta globin locus by transcription factors and chromatin modifiers. EMBO J 2000; 19:4986-96. [PMID: 10990462 PMCID: PMC314215 DOI: 10.1093/emboj/19.18.4986] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Locus control regions (LCRs) alleviate chromatin-mediated transcriptional repression. Incomplete LCRs partially lose this property when integrated in transcriptionally restrictive genomic regions such as centromeres. This frequently results in position effect variegation (PEV), i.e. the suppression of expression in a proportion of the cells. Here we show that this PEV is influenced by the heterochromatic protein SUV39H1 and by the Polycomb group proteins M33 and BMI-1. A concentration variation of these proteins modulates the proportion of cells expressing human globins in a locus-dependent manner. Similarly, the transcription factors Sp1 or erythroid Krüppel-like factor (EKLF) also influence PEV, characterized by a change in the number of expressing cells and the chromatin structure of the locus. However, in contrast to results obtained in a euchromatic locus, EKLF influences the expression of the gamma- more than the beta-globin genes, suggesting that the relief of silencing is caused by the binding of EKLF to the LCR and that genes at an LCR proximal position are more likely to be in an open chromatin state than genes at a distal position.
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Affiliation(s)
- T McMorrow
- Department of Cell Biology and Genetics, Medical Genetics Centre, Faculty of Medicine, Erasmus University Rotterdam
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Calzolari R, McMorrow T, Yannoutsos N, Langeveld A, Grosveld F. Deletion of a region that is a candidate for the difference between the deletion forms of hereditary persistence of fetal hemoglobin and deltabeta-thalassemia affects beta- but not gamma-globin gene expression. EMBO J 1999; 18:949-58. [PMID: 10022837 PMCID: PMC1171187 DOI: 10.1093/emboj/18.4.949] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The analysis of a number of cases of beta-globin thalassemia and hereditary persistence of fetal hemoglobin (HPFH) due to large deletions in the beta-globin locus has led to the identification of several DNA elements that have been implicated in the switch from human fetal gamma- to adult beta-globin gene expression. We have tested this hypothesis for an element that covers the minimal distance between the thalassemia and HPFH deletions and is thought to be responsible for the difference between a deletion HPFH and deltabeta-thalassemia, located 5' of the delta-globin gene. This element has been deleted from a yeast artificial chromosome (YAC) containing the complete human beta-globin locus. Analysis of this modified YAC in transgenic mice shows that early embryonic expression is unaffected, but in the fetal liver it is subject to position effects. In addition, the efficiency of transcription of the beta-globin gene is decreased, but the developmental silencing of the gamma-globin genes is unaffected by the deletion. These results show that the deleted element is involved in the activation of the beta-globin gene perhaps through the loss of a structural function required for gene activation by long-range interactions.
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Affiliation(s)
- R Calzolari
- Department of Cell Biology and Genetics, Medical Genetics Centre, Faculty of Medicine, Erasmus University, PO Box 1738, 3000 DR Rotterdam, The Netherlands
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Grosveld F, de Boer E, Dillon N, Gribnau J, McMorrow T, Milot E, Trimborn T, Wijgerde M, Fraser P. The dynamics of globin gene expression and position effects. Novartis Found Symp 1998; 214:67-79; discussion 79-86. [PMID: 9601012 DOI: 10.1002/9780470515501.ch5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We have used gene competition to study the regulation of the human beta-globin locus in transgenic mice as a model system of a multigene locus. The locus is regulated by the locus control region (LCR), which is required for the expression of all the genes. Analysis of the locus at the single-cell level shows that the LCR appears to interact directly with the genes via a looping mechanism. This interaction is monogenic, and the level of transcription is determined by the frequency and stability of LCR/gene complex formation. These parameters are dependent both on the distance between the LCR and gene(s), and the concentration of transcription factors in the nucleus. Disturbance of complex formation leads to position effects, particularly when the locus is integrated in a heterochromatic environment.
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Affiliation(s)
- F Grosveld
- MGC-Department of Cell Biology, Erasmus University, Rotterdam, The Netherlands
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Abstract
The presence of a haemoglobin protein which does not exhibit a Bohr effect has been found only in fish living in fast flowing waters. We report the cloning of the first non-Bohr effect beta-globin cDNA from an adult Atlantic salmon kidney bank. Nucleotide sequence analysis of this cDNA shows that the predicted beta-globin peptide comprises 147 amino acids with a calculated molecular mass of 15 975 Da and an overall amino acid homology of 40 to 50% to higher vertebrates and 60-90% to fish sequences. This sequence confirms the important amino acid residues which are changed thus causing loss of the Bohr effect [Powers, D.A. and Edmunson, A.B. (1972) Multiple hemoglobins of catostomid fish. J. Biol. Chem. 247, 6686-6693; Brunori, M. (1975) Molecular adaptation to physiological requirements: the hemoglobin system of trout. Curr. Topics Cell. Regul. 9, 1-39]. This loss allows the haemoglobin protein to have a higher oxygen affinity, as it does not release oxygen when the pH of the surrounding environment decreases, which is an important ability for the fish in times of stress.
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Affiliation(s)
- T McMorrow
- Microbiology Department, University College, Galway, Ireland.
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Abstract
Preliminary analysis of Atlantic salmon alpha- and beta-globin genes indicated that these genes are linked in a 3' to 3' orientation, with the RNA-coding sequences located on opposite strands. In this report, we show that two different alpha-globin genes have the same orientation and are encoded on the same strand whereas two different beta-globin genes are encoded on the opposite strand and also have the same orientation. This cluster of globin genes is divided into two subclusters: one for the Bohr globin genes and one for the non-Bohr globin genes. This is the first evidence for this type of arrangement found for globin genes. DNase I footprint analysis of two of the globin promoters show erythroid-specific transcription factor binding sites that have also been found in human and other mammalian globin genes.
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Affiliation(s)
- T McMorrow
- Microbiology Department, and National Diagnostics Centre, BioResearch Ireland, University College, Galway, Ireland
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Deryckere F, Byrnes L, Wagner A, McMorrow T, Gannon F. Salmon HNF1: cDNA sequence, evolution, tissue specificity and binding to the salmon serum albumin promoter. J Mol Biol 1995; 247:1-10. [PMID: 7897653 DOI: 10.1006/jmbi.1994.0115] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
cDNA clones coding for the transcription factor HNF1 have been isolated from Atlantic salmon (Salmo salar L.). The 559 amino acid residue long encoded protein shows high conservation, with respect to other species, of the domains necessary for DNA-binding: the HNF1 atypical homeodomain, the POU related sequence and the dimerisation domain. Alignment with rat HNF1 protein reveals that the transcription activation domains ADI and ADIII are relatively conserved in the fish sequence whereas ADII is not. Phylogenetic analysis indicates that higher vertebrate HNF1s and the related variant HNF1s (vHNF1s) are more closely related to each other than any of them is to Salmon HNF1, suggesting that the duplication event from which HNF1 and vHNF1 genes arose occurred after the divergence of the tetrapod and teleost ancestors. Northern blot analysis show a single transcript, of about 2.6 kb, which is not exclusive to liver but is also present in intestine, kidney and spleen. Using polymerase chain reaction (PCR) we have isolated the salmon albumin gene promoter which contains, upstream of the TATA box, a potential binding site for HNF1. The salmon HNF1 protein synthesized by in vitro transcription-translation of the full-length cDNA is able to bind specifically with equivalent affinities to either the rat or salmon albumin promoter.
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Affiliation(s)
- F Deryckere
- National Diagnostics Centre/BioResearch Ireland, Department of Microbiology, University College Galway
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Abstract
We report the cloning of a cDNA and two corresponding beta-globin genes of the Atlantic salmon (Salmo salar L.) as well as two genes for alpha-globins. Nucleotide sequence analysis of the cDNA shows that the predicted beta-globin peptide comprises 148 amino acids with a calculated molecular mass of 16,127 Da and an overall amino acid similarity of 40-50% to higher vertebrates and 60-90% to fish sequences. The study of the genomic organization of alpha- and beta-globin genes shows that, as is the case in Xenopus, the salmon genes are adjacent. Two sets of linked alpha- and beta-globin genes were isolated and restriction-enzyme polymorphisms indicate that they belong to two distinct loci, possibly as a result of the salmon tetraploidy. In each locus the alpha- and beta-globin genes are oriented 3' to 3' relative to each other with the RNA coding sequences located on opposite DNA strands. This is the first evidence for this type of arrangement found for globin genes. Moreover, while the linkage found in salmon and Xenopus supports the hypothesis of an initial tandem duplication of a globin ancestor gene, our results raise the question of the actual original orientation of the duplicated genes.
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Affiliation(s)
- A Wagner
- National Diagnostics Centre/BioResearch Ireland, Department of Microbiology, University College, Galway
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Pahwa RN, Modak MJ, McMorrow T, Pahwa S, Fernandes G, Good RA. Terminal deoxynucleotidyl transferase (TdT) enzyme in thymus and bone marrow. I. Age-associated decline of TdT in humans and mice. Cell Immunol 1981; 58:39-48. [PMID: 6971708 DOI: 10.1016/0008-8749(81)90147-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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